Recently, a lifting platform on the table surface has gradually gained popularity in daily life for various purposes such as study, office work, entertainment and the like. The device usually comprises a table plate, a base and a lifting device. The table plate is connected to the base through a lifting device, and the base is placed on the table surface. The lifting platform in the prior art is generally provided with a keyboard holder, and the keyboard holder is connected with a base of the lifting platform through a bracket. The connection mode of the keyboard holder is generally fixedly connection with screws. One of the defects of this structure is that the keyboard holder must be disassembled and assembled by means of a manual tool, thus more time-consuming and troublesome, and cannot meet the requirement for fast dismounting and assembling. Another sample of the lifting platform in the prior art includes a keyboard holder which is detachably inserted into the lifting platform, a fixed connecting plate arranged on the table plate, and a hanging plate arranged on the keyboard holder. The hanging plate is hung and connected to the fixed connecting plate. One of the defects of this electric lifting platform with hanging keyboard holder is that the height of the keyboard holder usually be adjusted at the position of a fixed point due to the hanging connection, and the keyboard holder cannot be locked at any height at any time, which leads to limited height selection range of the keyboard holder and a small group of users to coordinate; in addition, in order to meet the ergonomic requirements, the keyboard holder is arranged below the working table surface in a common computer desk, however the lowest position of the keyboard holder of the electric lifting platform in the prior art is located at the working table surface, and cannot be adjusted to the position below the working table surface, therefore, the keyboard holder of the electric lifting platform in the prior art does not meet the ergonomic requirements.